[vsnet-grb-info 17068] GRB 151001A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18381
SUBJECT: GRB 151001A: Swift/UVOT Detection
DATE:    15/10/02 12:44:45 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld at ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and M. Stamatikos (OSU/NASA/GSFC) report on 
behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 151001A 46 
s after the BAT trigger (Stamatikos et al., GCN Circ. 18373).
A fading source consistent with the enhanced XRT position (Beardmore et 
al. GCN Circ. 18376) is detected in the initial UVOT exposures.

The preliminary UVOT position is:
     RA  (J2000) =  15:34:54.90 = 233.72875 (deg.)
     Dec (J2000) = +10:58:02.2  =  10.96728 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT 
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for 
the early exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               67          217          147         17.82 ± 0.06
white              559          578           20         19.5  ± 0.3
v                   46         1403          110         18.78 ± 0.29
b                  534         1502           97         19.60 ± 0.29
u                  279          529          246         19.13 ± 0.15
w1                 657         1453           97        >19.3
m2                 806         1428           39        >18.0
w2                1358         1552           39        >18.4

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.04 in the direction of the 
burst (Schlegel et al. 1998).